Hydrogen peroxide (H 2O 2) residues are not permitted in food due to health concerns. An amperometric sensor based on a Nafion modified palladium (Pd) electrode was developed for the rapid determination of the H 2O 2 residue in aseptically packaged beverages. A prepared Pd electrode shows a slowly increasing reaction upon repeating the procedure of adding the same concentration of H 2O 2 into the reaction cell unless pretreating the electrode with cyclic voltammetry to obtain reproducible surfaces, whereas a Nafion modified Pd electrode can reach stable reaction to H 2O 2 without any pretreatment. The interference level of ascorbic acid (the ration of electrochemical response to ascorbic acid to the electrochemical response of H 2O 2) was calculated as 0.0004 for the Nafion modified Pd electrode. Interference (99.5%)from ascorbic acid was diminished by Nafion membrane. The response of the sensor to H 2O 2 in distilled water is linear over the range of 0.25-15 μM (r 2 = 0.9956). The sensor developed in this study can efficiently determine H 2O 2 residues in commercial beverages with good linear correlation between spiked H 2O 2 concentration and detected H 2O 2 concentration, for winter melon-flavored drink, r 2 = 0.9904 in the range of 0.25-15 μM and for lemon-flavored tea, r 2 = 0.9927 in the range of 0.25-25 μM. ? 2007 Springer-Verlag.
